An ink-jet apparatus is known as an apparatus having a head capable of applying a necessary amount of ink according to an input signal. In particular, piezo (piezoelectric) ink-jet apparatuses are currently objects of active development because of their ability to apply a wide variety of inks under precise control.
A piezo ink-jet apparatus is generally composed of an ink supply channel, a plurality of ink chambers that communicate with the ink supply channel and have a nozzle, and piezoelectric elements that apply pressure to ink loaded in the ink chambers (see Patent Literature 1 through Patent Literature 3 listed below, for example). In an ink-jet apparatus, when a drive voltage is applied to a piezoelectric element, the piezoelectric element is mechanically distorted. By this means, pressure is applied to ink inside an ink chamber, and an ink drop is discharged from a nozzle.
Air may be mixed in with ink inside an ink-jet apparatus, or an ink-jet apparatus nozzle may become clogged, which disables proper ink discharge. Thus, a technology is known whereby an ink-jet apparatus is provided with an ink evacuation channel that communicates with an ink chamber and through which ink evacuated from the ink chamber flows. Then, ink is made to flow from the ink supply channel to the ink evacuation channel using an ink circulating section such as a pump (see Patent Literature 4 listed below, for example).
FIG. 1 is a schematic diagram of an ink-circulating type of ink-jet apparatus disclosed in Patent Literature 4. As shown in FIG. 1, the ink-jet apparatus disclosed in Patent Literature 4 has ink supply channel 10, ink evacuation channel 11, and ink chambers 12A through 12C. Ink chambers 12A through 12C each communicate with ink supply channel 10 and ink evacuation channel 11. That is to say, ink chambers 12A through 12C communicate with ink supply channel 10 via communicating apertures 16A through 16C, and communicate with ink evacuation channel 11 via communicating apertures 17A through 17C. Ink chambers 12A through 12C have actuators 13A through 13C, and nozzles 14A through 14C.
As shown in FIG. 1, ink that is supplied from ink supply aperture 50 and flows through ink supply channel 10 is supplied to each of ink chambers 12A through 12C. Some of the ink supplied to each of ink chambers 12A through 12C is discharged as a droplet through the action of actuators 13A through 13C, and the remaining ink is supplied to ink evacuation channel 11 and evacuated from ink outlet 51.
By making ink flow from an ink supply channel to an ink evacuation channel via the ink chambers in this way, fresh ink is constantly supplied to the ink chambers, and it is possible to prevent air being mixed in with the ink and nozzles becoming clogged.
In the technology of Patent Literature 4, ink circulation pressure is supplied by an ink circulating section such as a pump, but a method is also known whereby a first piezoelectric element and second piezoelectric element are provided, and circulation pressure is supplied to the ink by driving the first piezoelectric element and second piezoelectric element at predetermined timings (see Patent Literature 5 and Patent Literature 6 listed below, for example).